Stanford is more selective, but USC students are far from stupid.
Stanford:
3.95 GPA, 4.8% admission rate
https://www.prepscholar.com/sat/s/colleges/Stanford-admission-requirements
USC:
3.73 GPA, 16% admission rate
https://www.prepscholar.com/sat/s/colleges/USC-admission-requirements
See my post #49. :)